FIELD OF THE INVENTION
[0001] The present invention relates to rotary shear valves, and more particularly, relates
to shear valves that incorporate hard-on-hard sealing surfaces.
BACKGROUND OF THE INVENTION
[0002] Current high pressure liquid chromatography shear valves typically employ a metallic
element and a rotor device composed of a polymer material that forms fluid-tight seal
at a rotor/stator interface. While this combination has been found to be successful,
it is limited in pressure rating and valve lifetime. For example, applications requiring
high pressures above 15 Kpsi and a lifetime greater than about 10K cycles are not
consistently attainable and sustainable using this combination.
[0003] US 2003/0196700 describes a valve assembly comprising a valve stem, an annular bonnet to receive
the valve stem, a valve disk coupled to one end of the valve stem, a seal, and an
insert. The seal is disposed adjacent the valve disk and has a top surface including
a first pair of sealing ridges extending upwardly and a bottom surface including a
second pair of sealing ridges extending downwardly. The insert includes a recess configured
to receive the seal that performs a sealing function and a biasing function.
[0004] US 2011/006237 describes rotary shear valves as described below with reference to Figures 1 to 24.
[0005] EP 0508749 describes a sampling valve for sampling blood having a movable element between a
pair of fixed elements. To prevent frictional sticking, lubricant is provided in a
reservoir around the movable element and a recess extends round the outer periphery
of each pair of abutting sliding surfaces of the fixed and movable elements.
[0006] GB 2213912 describes a fluid flow control valve for fitting between a radiator and a wet central
heating system which uses elastomeric seals between rotary and non-rotary members.
[0007] Accordingly, it is desirable to provide a shear face valve capable of holding pressures
greater than about 15 Kpsi that have expected valve lifetimes greater than 50K cycles.
SUMMARY OF THE INVENTION
[0008] A first aspect of the invention provides a high pressure rotary shear valve assembly
comprising: a stator device defining a substantially hard, substantially planar stator
face and at least two or more stator channels in fluid communication with said stator
face at corresponding stator ports, wherein the stator face terminates at an outer
circumferential edge; a rotor device having a substantially hard, substantially planar
rotor face defining one or more rotor channels, the rotor face extending radially
beyond the outer circumferential edge of the stator face when said rotor device is
rotatably mounted about a rotational axis to the stator device in a manner enabling
fluid-tight, selective relative rotation between the rotor face and the stator face,
at a rotor-stator interface, between two or more rotor positions; and a polymer insert
device defining an exposed contact face having an insert inner diameter less than
that of said outer circumferential edge and an insert outer diameter more than said
outer circumferential edge, said insert device being formed and dimensioned for press-fit
insertion in a receiving groove defined in the rotor face such that the outer circumferential
edge of the stator face rotatably contacts the insert exposed face between the insert
inner diameter and the insert outer diameter during said relative rotation between
said two or more rotor positions.
[0009] In one specific embodiment, the insert exposed face can be donut-shaped and substantially
planar. Further, the receiving groove and the insert device can cooperate to position
the substantially planar insert exposed face substantially flush with the other of
the substantially planar rotor face and the substantially planar stator face.
[0010] In another configuration, a groove inner diameter of the insert receiving groove
can be in the range of about 0.0254mm (0.001 inch) to about 0.0508mm (0.002 inch)
greater than that of an insert inner diameter of the insert device.
[0011] In yet another specific embodiment, the polymer insert device can be composed of
a high compressive strength material, which includes a natural PAEK, a filled PAEK
(or PEEK) or a polyimide material such as VESPEL®.
[0012] Still another configuration can provide the stator face and the rotor face as being
composed substantially of one of a metallic material and a ceramic material.
[0013] The valve assembly can further include, in another embodiment, a tribological coating
disposed atop at least one of the rotor face and the stator face. Such a coating,
for instance, can be a Diamond Like Carbon coating (DLC).
[0014] In yet another specific configuration, the valve assembly can further include a compliance
assembly cooperating with the rotor device in a manner orienting the substantially
planar rotor face substantially parallel to and substantially flush against the substantially
planar stator face of the stator device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The assembly of the present invention has other objects and features of advantage
which will be more readily apparent from the following description of the best mode
of carrying out the invention and the appended claims, when taken in conjunction with
the accompanying drawings, in which:
FIGURE 1 is a top perspective view of a micro-fluidic valve assembly that incorporates
both a metallic rotor element and a metallic stator element designed in accordance
with the prior art.
FIGURE 2 is a bottom perspective view of the micro-fluidic valve assembly of FIGURE
1.
FIGURE 3 is a top perspective view of the micro-fluidic valve assembly of FIGURE 1,
illustrating the rotor element with a stator ring and stator element removed.
FIGURE 4 is a side perspective view of the micro-fluidic valve assembly of FIGURE
1, illustrated with the stator ring removed.
FIGURE 5 is an exploded, top perspective view of a rotor assembly and the stator element
of the micro-fluidic valve assembly of FIGURE 1.
FIGURE 5 is an exploded, top perspective view of a rotor assembly and the stator element
of the micro-fluidic valve assembly of FIGURE 1.
FIGURE 6 is an enlarged, top perspective view of the rotor assembly of FIGURE 5.
FIGURE 7 is a partially exploded, top perspective view of the rotor assembly of FIGURE
6, incorporating a compliance assembly.
FIGURE 8 is a reduced, exploded, bottom perspective view of the micro-fluidic valve
assembly of FIGURE 1.
FIGURE 9 is a top perspective view of the rotor assembly incorporating an alternative
compliance assembly.
FIGURE 10 is a partially exploded, top perspective view of the rotor assembly and
compliance assembly of FIGURE 9.
FIGURE 11 is an exploded, top perspective view of the rotor assembly and compliance
assembly of FIGURE 9, together with the stator element.
FIGURE 12 is an exploded, bottom perspective view of the rotor assembly and compliance
assembly of FIGURE 10.
FIGURE 13 is an enlarged, fragmentary, side elevation view, in cross-section, of the
micro-fluidic valve assembly of FIGURE 1, incorporating the compliance assembly of
FIGURE 9.
FIGURE 14 is a side elevation view, in cross-section, of the compliance assembly of
FIGURE 13.
FIGURE 15 is a top perspective view of the rotor assembly incorporating another alternative
compliance assembly.
FIGURE 16 is an exploded, top perspective view of the rotor assembly and compliance
assembly of FIGURE 15.
FIGURE 17 is an exploded, bottom perspective view of the rotor assembly and compliance
assembly of FIGURE 15.
FIGURE 18 is a side elevation view, in cross-section, of the rotor assembly and compliance
assembly of FIGURE 15.
FIGURE 19 is a side elevation view, in cross-section, of the micro-fluidic valve assembly
of FIGURE 1, incorporating the compliance assembly of FIGURE 15.
FIGURE 20 is a partially exploded, side perspective view of the rotor assembly and
compliance assembly of FIGURE 15.
FIGURE 21 is an exploded, bottom perspective view of the rotor assembly and compliance
assembly of FIGURE 15.
FIGURE 22 is an enlarged, exploded, bottom perspective view of the compliance assembly
of FIGURE 15.
FIGURE 23 is an enlarged, exploded, top perspective view of the compliance assembly
of FIGURE 15.
FIGURE 24 is an enlarged, top plan view of the compliance assembly of FIGURE 15.
FIGURE 25 is an enlarged, fragmentary, side elevation view, in cross-section, of an
embodiment valve assembly incorporating a polymer insert device in accordance with
the present invention.
FIGURE 26 is an exploded, top perspective view of the rotor device of FIGURE 25, illustrating
the polymer insert device prior to insertion into a receiving groove.
FIGURE 27 is a top perspective view of the rotor device of FIGURE 25, illustrating
the polymer insert device press-fit into the receiving groove.
FIGURE 28 is an enlarged top plan view of the of the rotor device of FIGURE 27.
FIGURE 29 is a side elevation view, in cross-section, of the of the rotor device of
FIGURE 28.
FIGURE 30 is an enlarged, fragmentary, top perspective view of the rotor device and
insert device of FIGURE 29.
FIGURE 31 is a slightly exploded, enlarged, fragmentary, top perspective view of the
rotor device and stator device of FIGURE 25, showing the outer circumferential portion.
FIGURE 32 is an enlarged, fragmentary, side elevation view, in cross-section, of an
alternative embodiment of the valve assembly of FIGURE 25, incorporating an alignment
pin.
DETAILED DESCRIPTION OF THE INVENTION
[0016] While the present invention will be described with reference to a few specific embodiments,
the description is illustrative of the invention and is not to be construed as limiting
the invention. Various modifications to the present invention can be made to the preferred
embodiments by those skilled in the art without departing from the scope of the invention
as defined by the appended claims. It will be noted here that for a better understanding,
like components are designated by like reference numerals throughout the various figures.
[0017] Referring now generally to FIGURES 1-8, a rotary shear valve assembly 20 is provided
that includes a stator device 21 having a substantially metallic or ceramic, substantially
planar stator face 22. The stator device defines at least two or more stator channels
in fluid communication with stator face at corresponding stator ports 23. The valve
assembly 20 further includes a rotor device 25 having a substantially metallic or
ceramic, substantially planar rotor face 26. A tribological coating is disposed atop
at least one of the rotor face and the stator face. Thus, when the rotor device 25
is rotatably mounted about a rotational axis for selective relative rotation between
the rotor face and the stator face, at a rotor-stator interface, a fluid-tight seal
is formed between the two metallic faces during relative rotation between two or more
rotor positions.
[0018] Accordingly, due in part to the tribological coating, a metal-on-metal fluid-tight
seal is formed at the rotor/stator interface for high pressure applications (i.e.,15
Kpsi to about 25 Kpsi) that is also capable of sustaining high lifecycle capacity
(i.e., at least about 50K cycles). Such a tribological coating on at least one of
the rotor face and/or stator face enables the formation of a durable fluid-tight and
low friction seal under the necessary high pressure compressive pressures between
the stator device and the rotor device.
[0019] As will be described, at least the rotor face 26 and the stator face 22 are both
composed of a relatively rigid material for increased durability under high compression
forces. In other configurations, the entire rotor device 25 and the stator device
21 is composed of a substantially rigid material.
[0020] Preferably, both the rotor device and the stator device are comprised of metallic
compositions such as 316 Stainless Steel, Duplex Stainless Steel, titanium, Alloy
Steels or Tool Steel compositions. Other suitable rigid materials, however, have been
found that yield similar high pressure ability together with a high lifecycle capacity
can be applied, as long as a suitable tribological coating is disposed atop at least
one of the rotor face 26 and/or the stator face 22. One such suitable material family
is ceramics, for instance, such as Alumina, SSIC, Zirconia. It will be appreciated,
however, that whether the rotor and stator is composed of a metal or a ceramic material,
that material must be capable of being coated with the tribological material.
[0021] Coating of at least one of the stator face and/or the rotor face has been found necessary
in these high pressure applications in order to form a fluid-tight, low friction seal
at the rotor/stator interface. Due to the substantially rigid material composition
of the rotor face and the stator face, for the aforementioned desired reasons, these
rigid materials are of course relatively non-compliable.
[0022] Such a coating, however, must also exhibit sufficient structural integrity for a
high lifecycle under these high fluid pressure, high compressive force conditions.
One such suitable and effective coating for pressurized fluid-tight seal formation
between opposed rigid surface interfaces, under these conditions, is the tribological
coatings. These coatings have been found to exhibit high strength (toughness) and
low friction, as well as being resistant to most chemicals used in Liquid Chromatography.
[0023] One specific tribological coating that is particularly suitable for this application
is the Diamond Like Carbon coatings (DLC), such as the BALINIT® DLC STAR and BALINIT®
DLC provided by Balzers Oerlikon or the aDLC provided by Ionbond. Other tribological
coatings that exhibit these characteristics, however, can be applied.
[0024] At least one of, or both, the stator face and the rotor face 26 is coated with the
tribological material. In certain conditions, applying the tribological coating to
the stator face 22 of the stator boss 27 has been found particularly advantageous
to provide a stronger, longer lasting fluid-tight seal at the rotor- stator interface
(FIGURE 8). For example, for high fluid pressure applications (i.e., greater than
about 18 Kpsi, higher axial compression forces between the rotor face 26 and stator
face 22 are necessary to maintain a fluid-tight seal. When the valve is set (i.e.,
when the pressure adjuster nut is adjusted until a rate of decay is achieved, typically
this rate is 0.3 uL/min. Fluid pressure is applied to the valve through the stator
port(s) rotor seal groove(s). Once the valve holds the required amount of pressure
(15-25 Kpsi in this instance) at the 0.3 uL/min leak rate, the valve is "set". The
high pressure applied to the seal by a spring assembly 30 (that includes an adjuster
nut 31 and spring washers 32 (FIGURE 8)) occasionally causes the coating seal to be
indented by the circumferential edge portion of the stator boss 27. Thus, if the rotor
face 26 is coated (e.g., the rotor face alone or in combination with the stator face),
inconsistent results and damage components have been observed in these instances due
to cracking of the coating, or delaminating at the edge portion as the valve is actuated.
[0025] It is believed that this indentation causes the coating to "flake-off" or delaminate
from the rotor seal in the area of the indentation as the valve is actuated. As this
coating is removed, the debris, and possibly the uncoated metal, has been observed
to score the remaining coating, degrading the integrity of the coating on the stator
boss, and causing the coating on the stator to fail. Once this degradation commences,
the fluid-tight seal at the rotor/stator interface will fail in holding pressure.
[0026] When only the stator face is coated with the tribological coating, under these high
pressure applications, this degradation is not observed. It will further be noted
that at lower pressures (3-6 Kpsi), it is believed that both the stator and rotor
seal could be coated (DLC or otherwise) and provide a good seal, since hard-on-hard
valves work at these pressures. Since these pressures applied to the seal would be
lower, the rotor seal is less likely to be indented and cause the coating to fail.
[0027] Referring now to FIGURES 1-5 and 8, a typical shear valve assembly 20 is shown and
described. Briefly, as best illustrated in FIGURE 8, the shear valve assembly typically
includes a housing assembly 33 (essentially comprised of a valve housing and a stator
ring) upon which a rotor assembly 29 is rotatably disposed therein. The rotor assembly
29 includes a drive shaft 35 and a distally disposed head assembly 36 that is configured
to seat the rotor device 25 thereon. To promote force concentration and the ability
of the rotor device to pivot atop the head assembly 36, the head assembly includes
a raised platform or pad 34 upstanding slightly from a distal surface 38 thereof.
This upstanding shaft pad 34 is preferably disk-shaped, having a substantially planar
seating surface 39 that is configured to seat directly against a contact surface 40
of the rotor device 25. It will be appreciated, however, that FIGURES 5, 7 and 8 are
illustrated with a thin compliant element or shim member 44 disposed there between
which will be described in detail below.
[0028] The diameter of this upstanding pad 34 is preferably less than that of the contact
surface 40 of the rotor device. However, the diameter is also preferably not less
than a range of about 45% that of the rotor device, such that the smaller diameter
allows minute teetering of the rotor device so that the rotor face and stator face
will be in full contact therebetween. Accordingly, as will be described in greater
detail below, the contact surface 40 of the rotor device 25 and seating surface 39
of the upstanding shaft pad 34 need not be in substantially flush contact with one
another. The diameter of the upstanding pad may be in the range of about 5.08mm (0.200")
to about 9.3472mm (0.368"), and more preferably about 5.842mm (0.230"), while the
diameter of the rotor device may be in the range of about 15.24mm (0.600") to about
15.875mm (0.625").
[0029] In a typical configuration, three strategically oriented dowel pins 37 extend distally
from the distal surface 38 of the head assembly 36 (FIGURES 5-7). These dowel pins
37 are slideably received in corresponding through-holes 41 in the disk-shaped rotor
device 25 that function to mount and align the rotor device 25 relative to the drive
shaft 35. Furthermore, these dowel pins 37 enable torque transfer, and thus, rotation
of the rotor device 25 as the drive shaft 35 is rotated about the rotational axis.
[0030] The stator device 21 is mounted to a distal portion 42 of the housing assembly 33,
via nuts 43, in a manner positioning the stator face 22 of the stator boss adjacent
to and in contact with the rotor face 26 of the rotor device 25. To generate the compressive
force between the rotor device 25 and the stator device 21, at the rotor-stator interface,
the spring assembly 30 is cooperates between the housing assembly 33 and the head
assembly of the drive shaft 35. Briefly, a pressure adjuster nut 31 is threadably
mounted to the proximal portion of the housing assembly 33. As the distal end of the
pressure adjuster nut compresses a spring stack (i.e., the stack of spring washers
32) against the head assembly 36 the rotor device 25 is compressively urged against
the stator boss 27. Newer micro-fluidic valves have recently been developed that incorporate
pressure adjuster assemblies for ultra-high pressure fluid applications that offer
significant valve rebuild advantages. These assemblies are disclosed in U.S. Patent
Application Publication Number
US 2011/0303304 to Tower et al, filed June 14, 2010, entitled "REBUILDABLE MICRO-FLUIDIC VALVE ASSEMBLY ".
[0031] Referring now to FIGURES 3-7, both the stator device 21 and the rotor device 25 are
composed of a metallic material, forming a metal-on- metal stator-rotor interface.
The tribological coating (preferably a DLC) isolates true metal-to- metal contact,
of course, functioning to form a fluid-tight seal under higher pressure situations.
As indicated above, for applications greater than about 15 Kpsi, the stator face 22
is preferably coated, while for applications ranging from about 3 Kpsi to less than
about 6 Kpsi, either the stator face 22, the rotor face 26 or both faces can be coated.
[0032] In this coated, metal-on-metal configuration, due to the rigidity and hardness of
these shear face valve components, it is highly beneficial to orient the substantially
planar faces of the stator device and the rotor device substantially parallel to one
another. However, while such substantially parallel orientation is attainable, this
may be cost prohibitive, and thus not be practical. Due to the collective stack up
of component tolerances, the metal rotor face 26 may not seal flatly or substantially
parallel and flush to the substantially planar stator face, or the stator may not
be perfectly planar in the first place.
[0033] Therefore, the rotor assembly 29 incorporates a rotor face compliance assembly 45
that cooperates with the substantially planar rotor face 26 to orient it substantially
parallel to the stator face 22. The compliance assembly 45, for example, includes
a compliant element (e.g., a shim member 44 of FIGURES 5-8, or a support device 50
of FIGURES 9-13) disposed between the head assembly 36 and the rotor device 25 (or
at least metallic or ceramic portion thereof, such as the rotor element 46 of FIGURES
9-13) that is compressible in a manner enabling the substantially planar rotor face
26 to orient substantially parallel to the stator face 22. In one particular embodiment,
as above-mentioned, the compliant element is provided by a compliant shim member 44
disposed between the distal seating surface 39 of the raised platform 34 and the contact
surface 40 of the rotor assembly 29. Hence, upon compression of the head assembly
36 against the rotor device 25, and thus, compression of the rotor face against the
stator face, the substantially more compliant shim 44 will be caused to compress in
a manner that seats the rotor face more flush and parallel against stator face. As
mentioned above, thus, the need for a completely flush seat between the contact surface
40 of the rotor device 25 and the seating surface 39 of the upstanding shaft pad 34
is not as necessary to ensure a flush, sealed contact between the rotor face and the
stator face.
[0034] The diameter of the shim member 44 is preferably less than that of the contact surface
40 of the rotor device 25, but must incorporate through-holes 48 that are strategically
aligned to receive and cooperate with the dowel pins 37 that extend distally from
the distal surface 38 of the head assembly 36 (FIGURES 5-7). Similar to the rotor
device 25, these dowel pins 37 are slideably received in the corresponding through-holes
48 in the shim 44 to mount, secure and align the shim 44 relative to the head assembly
36.
[0035] As best shown in FIGURES 5, 7 and 8, the shim may be comprised of many different
shapes. For instance, the shim may be a conventional circular shape (FIGURE 8), or
may be an efficient, minute triangular shape (FIGURES 5 and 7).
[0036] The material composition of the shim 44 should have sufficient structural integrity
to withstand the substantial compressive forces applied between the rotor device and
the stator device. However, the material must also be sufficiently compliable to enable
the rotor face to seat substantially flush against the stator face, during operative
compression. The compressive modulus, k, for instance, is preferably in the range
of about 250 to about 300 kpsi. The material composition of the shim 44 may be comprised
of Polyethylene Terephthalete Glycol (PETG), Polyester or Polycarbonate, having a
thickness in the range of about 0.254mm (0.010") to about 1.016mm (0.040").
[0037] In another compliance assembly 45, as illustrated in FIGURES 9-12, the rotor device
25 is comprised of a metallic or ceramic (insertable) rotor element 46 that is received
and supported by a compliant support device 50. The support device 50 functions as
the compliant element, and thus, provides a compliant backing against the back side
(i.e., the proximal face) of the inserted rotor element 46. FIGURES 10-12 best illustrate
that the metallic rotor element 46 is preferably disk-shaped having the distal facing,
substantially planar rotor face 26 containing the rotor channels 47.
[0038] The support device 50 is for the most part is shaped similar to a typical rotor device
25, such as that in FIGURES 5-7. The distal face of the support device, however, defines
a receiving socket 51 with a peripheral interior sidewall 52 formed and dimensioned
for press-fit receipt of the outer circumferential or peripheral wall 53 of the rotor
element 46 until a proximal face 54 thereof contacts and is supported by the distal
socket face 55 of the receiving socket 51.
[0039] By providing a compliant backing material, at least in the axial direction, upon
the application of a compressive force between the rotor device 25 and the stator
face 22, the contacting surfaces of the support device 50 should have some compliance
or compression. Such compressive compliance allows the substantially planar rotor
face 26 to slightly relocate to an orientation that is substantially parallel to the
substantially planar stator face. In other words, the compliant material will "move"
or compress, due to contact with the backside contact surface of the metal rotor element,
allowing the polymer to absorb any misalignment between the rotor face and the stator
face of the stator boss. The rotor face 26 can then seal and mate flat against and
substantially parallel to the stator boss face 22.
[0040] The support device 50 is preferably about 2.54mm (0.100") to about 5.08mm (0.200")
thick, has a compressive modulus, k, in the range of about 4000 to about 5000 kpsi,
and is composed of a polymer material exhibiting high tensile and compressive strength.
Such a compliant material exhibiting these other properties, permits minute compliance,
while further permitting transfer of the high compressive forces in the axial direction
to the rotor face 26 of the rotor element 46. As best illustrated in FIGURES 13 and
14, compliance on the order of about 1° or about 0.127mm (0.005") at the circumferential
edges of the rotor element is attainable.
[0041] The polymer material used can be changed for a variety of applications. Depending
upon whether the application is for the lower region of what is considered a high
lower pressure application (e.g., 3-6 Kpsi), a softer unfilled polymer, such as PEEK™
or Nylon, may be applied. In contrast, for higher pressure applications (e.g., 15-25
Kpsi), a carbon filled polymer material may be necessary which significantly increases
the polymers tensile and compressive strength.
[0042] One such high strength polymer support material is an engineered blend of PEEK™ with
carbon fibers (e.g., a 20%-30% carbon PEEK™ blend). This polymer material is carbon
filled, yielding the requisite high tensile and compressive strength. Thus, due to
the high pressures of the spring washers 32 needed to seal the valve, this PEEK™ blend
is currently the preferred material. It will be appreciated, however, that other polymer
based materials, or even a higher strength elastomer could be used.
[0043] Turning now to FIGURES 10 and 11, the disk-shaped rotor element 46 is generally keyed.
Not only does this aligned the rotor face 26 relative to the drive shaft 35, but also
functions to facilitate torque transfer to the rotor element during the rotation of
the support device 50. For ease of machining, the rotor element 46 is "D" shaped and
the female receiving socket 51 is a modified "D" shape where the corners of the flat
have been relieved for the radius of an end mill. The two parts are assembled by using
an arbor press. The arbor press press-fits (0.0508mm (0.002") press fit) the two parts
together. It will be appreciated, of course, that the outer peripheral edges may be
any shape that enables the metal seal insert to press-fit into the polymer backing.
[0044] Referring now to FIGURES 16-24, the rotor assembly 29 incorporates an alternative
rotor face compliance assembly 45 that enables the rotor face to "rock" and/or "pivot"
to an orientation that allows the opposed rotor face and stator face to seal and mate
flushly against one another on the stator boss 27.
[0045] In this configuration, in a simplified description, a disk-shaped metallic rotor
element 60 (similar to that of FIGURES 16 and 20-23) is pivotally seated atop a ball
bearing 61, which in turn, is seated atop a distal end of the head assembly 36 of
the drive shaft 35. Accordingly, as a compressive force is applied to the drive shaft
35, the force is transferred, via the ball bearing 61, to the rotor element 60. Upon
increasing pressure between the adjacent, and opposed contact, at the rotor/stator
interface, the rotor element 60 is caused to minutely rock or pivot in an effort to
reorient and align the rotor face substantially parallel to the stator face.
[0046] To facilitate support of the pivoting rotor element 60, a drive ring 62 is provided
that is also shaped similar to the conventional rotor device it replaces. FIGURES
16 and 17 best illustrate that this drive ring includes an axially extending receiving
aperture 63 formed for axial receipt of the rotor element 60 in a manner allowing
the insert to "float" axially therein, while at the same time securing the rotor element
rotationally to the drive ring 62 for rotation about the rotational axis.
[0047] Accordingly, the inner diameter of the inner sidewall 66 that defines the receiving
aperture 63 is slightly larger than the diameter of the outer circumferential wall
67 of the rotor element 60 to permit minute pivotal movement thereof. The clearance,
for example, between the outer diameter of the seal insert and the inner diameter
of the drive ring is about 0.508mm (0.020") (0.254mm (0.010") per side). This allows
the seal insert to move laterally back and forth within the ring drive 0.254mm (0.010")
per side.
[0048] To provide seating support atop the ball bearing 61, the proximal facing surface
of the rotor element 60 includes a dome-shaped ball socket 68 that is formed, sized
and dimensioned to receive a portion of the ball bearing. This configuration is further
responsible for providing the pivotal support about ball bearing, and relative to
the drive ring 62.
[0049] To transfer torque to the axially free floating rotor element 60, as the drive ring
62 rotates about the drive shaft axis, a plurality of guide pins 70 extend radially
into the aperture 63 from the inner sidewall 66 of the drive ring 62. These radial
guide pins 70 are formed for sliding axial receipt in corresponding elongated receiving
slots 71 extending in an axial direction along the outer circumferential wall 67 of
the rotor element. Accordingly, as the drive ring is rotated, the guide pins 70 transfer
this rotational motion directly to the rotor element.
[0050] For precise and accurate rotational displacement and movement of the rotor element,
the tolerances between the diameter of the guide pins 70 and the width of the corresponding
receiving slots should therefore be relatively small. In one specific embodiment,
for example, the tolerance between the diameter of guide pins and the width of the
slots is approximately 0.0508mm (0.002") (0.0254mm (0.001") per side). For instance,
if the diameter of the guide pin is selected to be about 0.7366mm - 0.7874mm (0.029"
- 0.031"), then the width of the guide slot 71 in the rotor element should be selected
to be in the range of about 0.7874mm - 0.8382mm (0.031" - 0.033"). Such a relatively
small tolerance will enable substantially immediate transfer of the rotation of the
drive ring 62, about the drive shaft axis, directly to the rotor element 60. The relative
position of the rotor seal grooves 47 relative to the stator ports 23 can therefore
be accurately determined.
[0051] These radially spaced guide slots 71, however, also extend radially into the outer
circumferential wall 67 of the rotor element by a depth slightly greater than the
radial length of the guide pins 70. This tolerance permits guide pins 70 to extend
slightly into and out of the corresponding guide slots to enable the aforementioned
minute lateral movement (on the order of about 0.254mm (0.010") per side) of the rotor
device within the drive ring receiving aperture 63. Hence, as the rotor element 60
minutely pivots or rolls about the ball bearing, it also slides along the guide pins
70. This relative axial movement (as well as very minute, relative radial movement)
of the guide pins 70 axially along the corresponding receiving slots 71, while also
moving minutely laterally within the receiving aperture, enabling the substantially
planar rotor face 26 to slightly reorient substantially parallel to the stator face
22. Thus, unlike the polymer backed support device 50 of FIGURES 18-21, the compliance
from this pivotal version is provided by the ability of the rotor element seal insert
to "move" and "pivot" (i.e., roll) about the ball bearing until the rotor face is
reoriented substantially parallel to, and substantially flat against the stator face
22 of the stator boss 27.
[0052] These guide pins 70 can be provided by threaded screws (as shown and illustrated)
or can be molded or milled during formation of the drive ring 62. Moreover, while
five guide pins 70 are shown radially spaced about the inner sidewall 66 of the receiving
aperture 63, the compliance assembly 45 could function with only one guide pin and
corresponding slot (albeit a more limited compliance). A minimum of three radially
spaced guide pins and corresponding guide slots, however, are desired to provide an
increased scope of compliance.
[0053] An opposed domed-shape socket 72 is also defined by the distal face of the head assembly
36 that is formed to similarly seat against the ball bearing 61. Preferably, this
opposed domed-shape socket 72 is provided by an insertable dowel pin 73, press-fit
into a corresponding passage 75 at the distal end of the drive shaft 35.
[0054] Referring now to FIGURES 18 and 19, as a compression force, via spring assembly 30,
axially urges the drive shaft 35 toward the stator device 21, the dowel pin 73 compresses
the ball bearing 61. In turn, the ball bearing 61 transfers this axial compressive
force to the rotor element 60 to form the fluid-tight seal at the rotor-stator interface.
[0055] It will be appreciated that, in order to accommodate the high compressive forces
applied to the ball bearing, the diameter of the ball bearing should be at least about
½ (and preferably 2/3) the diameter of the rotor element 60. This assures that the
compressive forces will be more widely distributed about the domed-shaped socket 68
of the rotor element, as compared to a more concentrated force distribution should
the ball bearing be of a smaller diameter.
[0056] Through many trials of testing of tribological coatings, especially DLC coatings,
under ultra high pressure (UHP) applications (e.g., 20kpsi or higher), for the above-mentioned
hard-on- hard rotary valves (e.g., metal-on-metal or ceramic-on-metal valves), increased
wear has been observed in the tribological coatings, in certain contact regions, that
promote premature valve failure. In one example, as best viewed in FIGURES 25 and
31, a main region where excessive wear in the tribological coating has been observed
is at the outer circumferential portion 80 (particularly an outer circumferential
edge 81) of the stator boss 27. This outer portion is exposed to extremely high stress
and the highest velocity of the rotor seal during switching of the valve.
[0057] Consequently, cracking, flaking or delaminating of the tribological coating have
been observed whereupon the removed debris, and possibly the uncoated metal, is believed
to score the remaining coating, thereby degrading the integrity of the coating on
the stator boss, and causing the coating on the stator to fail. Again, once this degradation
commences, the fluid-tight seal at the rotor/stator interface will fail in holding
pressure.
[0058] In accordance with an aspect of the present invention and as best shown in FIGURES
25-31, a rotary shear valve assembly, generally designated 20, has been developed
that includes a stator device 21 and a rotor device 25. The stator device 21 defines
a substantially hard, substantially planar stator face 22 and at least two or more
stator channels 82 in fluid communication with the stator face 22 at corresponding
stator ports, while the rotor device 25 defines a substantially hard, substantially
planar rotor face 26 defining one or more rotor channels 47. One of the stator face
22 and the rotor face 26 terminates at an outer circumferential edge 81 (e.g., the
stator face 22 in particular embodiment of FIGURES 25 and 31), and the other of the
rotor face 26 and the stator face 22 extends radially beyond the outer circumferential
edge 81 of the one stator face 22 and the rotor face 26 when the rotor device 25 is
rotatably mounted about a rotational axis to the stator device 21. Such rotational
mounting cooperates in a manner enabling fluid-tight, selective relative rotation
between the rotor face 26 and the stator face 22, at a rotor-stator interface, between
two or more rotor positions. In accordance with the present invention, the valve assembly
20 includes a polymer insert device, generally designated 83, that is formed and dimensioned
for press-fit insertion into a receiving groove 85 defined in the other of the rotor
face 26 and the stator face 22 (e.g., the rotor face 26 in FIGURES 26 and 27) such
that the outer circumferential edge 81 of the one of the stator face 22 and the rotor
face 26 (e.g., the stator face 22 in FIGURES 25 and 31) contacts the insert device
83 during the relative rotation between the two or more rotor positions. The insert
device 83, in particular, defines an exposed contact face 86 that has an insert inner
diameter less than that of the outer circumferential edge 81 (e.g., the stator face
22 in FIGURE 31), and an insert outer diameter that is greater than that of the outer
circumferential edge.
[0059] Accordingly, the hard-on-hard (e.g., metal-on-metal or metal-on-ceramic) contact
between the rotor face 26 and the stator face 22, at the circumferential edge 81,
is essentially supplanted with contact between the polymer insert device 83 and the
hard circumferential edge. The rotating contact between the metallic and/or ceramic
circumferential edge 81 with the exposed contact face 86 of the polymer insert device,
at this outer circumferential portion 80, enables fluid-tight contact with the circumferential
edge 81, as well as providing sufficient deformation to substantially absorb the high
stress generated thereat. Since the tribological coating in this outer circumferential
portion 80, particularly at the outer circumferential edge 81, is now exposed to significantly
lower stresses, wear, scoring and/or chipping of the tribological coating is also
significantly reduced.
[0060] Due to the rotating contact between the stator face 22 and the exposed contact face
86 of the insert device, one important material property of the insert device 83 is
that the selected polymer performs well in a bearing application under UHP applications.
Moreover, while the selected polymer material of the insert device must exhibit high
compressive strength, its modulus of elasticity of about 1193 kpsi and a compressive
modulus of about 68.4 kpsi, it must be significantly less than that for a ceramic
or metallic material of the stator face and/or rotor face. This, of course, allows
the polymer insert device 83 to locally absorb the high stresses at these regions.
Examples of such suitable polymer materials include natural Polyaryletherketone (PAEK),
filled PAEK (e.g., PEEK®) or a polyimide material such as VESPEL®.
[0061] Briefly, while this aspect of the present invention is illustrated and thus described
with the outer circumferential edge 81 oriented along either of the stator face 22
or the rotor face 26 (e.g., the stator face 22 in FIGURES 25 and 31), and the other
of the rotor face 26 or the stator face 22 supports the opposed insert device 83 thereof,
for the ease of description, all reference henceforth relates to placement of the
insert device 83 with the rotor face 26. Moreover, it will be appreciated that FIGURE
31 illustrates the stator device 21 and the rotor device 25 minutely displaced from
one another for the ease of illustration. During operation of the valve assembly 20,
the rotor face 26 would be in rotating contact with the stator face 22.
[0062] As indicated above, in this particular embodiment, the stator device 21 of the valve
assembly 20 incorporates a down-standing stator boss 27. This boss is defined in part
by an annular outer circumferential side wall 87 that tapers inwardly, forming a conical-shaped
chamfer. This conical side wall 87 intersects the stator face 22, forming the outer
circumferential edge 81, in this embodiment.
[0063] Positioned in opposed contacting relationship to the outer circumferential portion
80 is the polymer insert device 83. This insert device is preferably ring -shaped
(FIGURES 26-29), having a substantially planar exposed contact face 86, and configured
to be press-fit disposed in a substantially similarly annular recess or receiving
groove 85, defined in the substantially planar rotor face 26. This receiving groove
is sized and dimensioned to cooperate with the insert device to fixedly retain the
insert to the rotor device 25, during valve operation, and to position the exposed
contact face 86 of the polymer insert device 83 substantially flush with that of the
substantially planar rotor face 26 when in compressive contact against the stator
face 22.
[0064] To assure contact and alignment of the stator circumferential edge 81 with the contact
face 86 of the insert device 83, the groove inner diametric edge 89 of the annular
groove 85 is sufficiently spaced radially inwardly from anticipated line of contact
between the insert device and the stator outer circumferential edge 81. The radial
position of the groove inner diametric edge, however, must sufficiently spaced from
an outer edge 88 of the rotor channel 47 so as to enable the formation of a fluid-tight
seal is between the stator face 22 and the rotor face under the aforementioned operating
conditions (i.e., ultra high pressure, such as 20 kpsi or higher, hard-on-hard applications).
In other words, the minimum outer radial depth, L1, between the rotor channel outer
edge 88 and the groove inner diametric edge 89 must be sufficient for fluid- tight
seal formation. In one specific embodiment, as best illustrated in FIGURES 30 and
31, the minimum outer radial depth, L1, between the rotor channel outer edge 88 and
the groove inner diametric edge 89 should be at least about as wide as the width,
WC, of the transverse cross section dimension of the rotor channel 47.
[0065] On the other hand, it will be appreciated that the minimum interior radial depth,
L2, between the groove inner diametric edge 89 and the region of contact with the
stator outer circumferential edge 81 to be at least about two times the rotor channel
width, WC. Such a minimum interior radial depth, L2, will assure rotational bearing
contact of the stator outer circumferential edge 81 with the exposed contact face
86 of the insert device 83.
[0066] Similarly, the groove outer diametric edge 90 is also sufficiently spaced radially
outward from the outer circumferential portion 80, particularly, the stator circumferential
edge 81, to assure contact therebetween. As best shown in FIGURE 31, the minimum outer
radial depth, L3, between the region of contact with the stator outer circumferential
edge 81 and the groove outer diametric edge 90 is preferably at least about as long
as the hypotenuse of the chamfer (i.e., the stator boss side wall 87).
[0067] The polymer insert device 83, as mentioned above, cooperates with the receiving groove
85 for press-fit receipt therein. Hence, the outer shell of the insert device 83 and
the interior walls defining the receiving groove 85 are similarly shaped, formed and
dimensioned, with-in predetermined tolerances. The press fit nature of the insert
around the inner diametric wall 91 should therefore be sufficient to fixedly retain
the insert within the receiving groove 85 during operation of the valve assembly,
while at the same time, not be so snug as to jeopardize the structural integrity of
the insert device 83. In one particular embodiment, for instance, a diameter of the
inner diametric wall 91 of the receiving groove 85 is on the order of about 0.0254mm
- 0.0508mm (0.001 - 0.002") greater than that of the inner wall 92 of the insert device
83 which, when press-fit over the groove inner diametric wall, will be adequate to
affix the polymer insert in place during valve operation under UHP applications.
[0068] By comparison, however, the polymer insert device 83 and the annular receiving groove
85 are machined such that the groove outer diameter is actually slightly larger than
that of the outer diameter of the insert device. This tolerance allows the polymer
insert device 83 to expand radially outward while under load. By way of example, the
diameter of outer diametric wall 93 of the receiving groove 85 is in the range of
about 0.127mm - 0.508mm (0.005" to about 0.020") larger than that of the outer wall
95 of the insert device, and more preferably in the range of about 0.254mm (0.010")
larger.
[0069] Accordingly, in one specific embodiment just described, the insert inner wall 92
and the groove inner diametric wall 91 interface cooperate in a press-fit manner,
while the insert outer wall 95 and the groove outer diametric wall 93 interface cooperate
in an expansive manner. It will be appreciated, however, that the insert outer wall
95 and the groove outer diametric wall 93 interface cooperate in the above-mentioned
press-fit manner, while the insert inner wall 92 and the groove inner diametric wall
91 interface cooperate in above-mentioned expansive manner. In yet another configuration,
both the inner and outer interfaces can be configured to cooperate in a press-fit
manner.
[0070] The minimum depth of the polymer insert device is selected to be in the range of
about 1.27mm (0.050") to a maximum depth in the range of about 3.556mm (0.140"), and
is more preferably about 1.27mm (0.050"). This depth of the polymer insert should
be sufficient to extend slightly above the rotor face at least initially, as will
be described below.
[0071] During fabrication and assembly, the initial height of the insert device 83, however,
is selected to be slightly taller than that of the receiving groove 85 so that the
exposed contact face 86 is slightly raised above the substantially planar rotor face
26 when the insert device 83 is fully received and inserted therein. Once the insert
device 83 has been press-fit around the groove inner diametric wall 91 and into the
receiving groove 85 of the rotor device 25, a lapping and polishing process is performed
on the rotor seal to procure a very shiny, smooth, substantially planar surface of
the rotor face. This procedure ensures that the rotor face 26 and the polymer contact
face 86 are substantially planar and substantially flush with one another. After this
lapping/polishing procedure, the rotor seal is cleaned and is ready to be assembled
into the valve assembly.
[0072] Applying the above-mentioned parameters, by way of example and in one particular
embodiment, the inner diameter of the insert device is about 3.2512mm (0.128") to
about 3.2766mm (0.129") while the outer diameter thereof is about 5.715mm (0.225").
By comparison, the inner diameter of the receiving groove is about 3.302mm (0.130")
while the outer diameter thereof is about 5.969mm (0.235").
[0073] As best viewed in FIGURE 32, the valve assembly 20 may incorporate an alignment pin
96 that facilitates precise alignment between rotor device 25 and the stator device
21, as well as relative to the head assembly 36. This alignment pin 96 upstands axially
from the shaft pad 34, and is formed for sliding receipt through an alignment aperture
97 extending axially through the rotor device 25. Axially aligned with the rotor alignment
aperture 97 is a stator alignment slot 98.
[0074] Accordingly, upon assembly of the rotor device 25 and the stator device 21 about
the alignment pin 96, the rotor face 26 and the stator face 22 are easily aligned,
properly aligning the stator outer circumferential edge 81 with the exposed contact
face 86.
[0075] Furthermore, while the present invention has been described in connection with the
preferred form of practicing it and modifications thereto, those of ordinary skill
in the art will understand that many other modifications can be made thereto within
the scope of the claims that follow. Accordingly, it is not intended that the scope
of the invention in any way be limited by the above description, but instead be determined
entirely by reference to the claims that follow.
[0076] For example, while the present invention is particularly suitable for hard-on-hard
UHP applications, it may also be applied in other lower pressure hard-on-hard applications
as a means to increase the valve life time.